Palaeogale undetermined

Palaeogale sp.

(Fig. 2; Table 1)

REFERRED SPECIMEN. — JODA 13221, Skull; Braincase broken on both sides, exposing endocase. Posterior sagittal crest absent. Zygomatic arches absent. Incisors and left premolar absent. Tympanic bulla broken exposing endocast.

LOCALITY. — JDNM-7B, North Foree, Grant County, Oregon, USA. Unit E2, Turtle Cove Member, John Day Formation. Precise locality information available to qualified researchers upon request.

AGE. — Middle Oligocene in the Early Arikareean (Ar1) NALMA, between A/B tuff (30.0 Ma) and Blue Basin Tuff (28.9 Ma) (Albright et al. 2008).

DESCRIPTION

JODA 13221 is a mostly complete skull. The braincase is broken on both sides, exposing endocase. Posterior sagittal crest is broken, and the zygomatic arches are broken. The tympanic bulla is broken, exposing the endocast. All Incisors are broken in the alveoli.The canines are missing but the alveoli are present and filled with matrix. Both P1s are missing and some matrix and dentine are present in the alveoli. The left P2 is broken at the roots which are lodged in the alveoli. The crown of the left P4 is damaged as is that of the left M1. The protocone of both the left and right M1s are present but are heavily worn.

Dentition

In the P4, the protocone is small and rounded. In the M1, the protocone is small but is worn so other characters are unknown. However, the M1 is triangular, transverse, short and wide, with a sharply projecting parastyle. Alveoli are present for both right and left P1. M2 is absent. See Table 1 for measurements.

Cranium

The skull is elongate (total length of 50.63 mm; max skull height of 14.76 mm) while the muzzle is short (14.50 mm from the naris to the orbit) making up about 29% of the total skull length.Tympanic bullae are elongate and rounded. The sagittal and occipital crests are damaged.

COMPARISON

There are no species level characters that are identified on the skull making a species level diagnosis impossible. Inference based on size is possible, but it lacks the rigor to justify a species-level diagnosis. It is likely that this specimen belongs to P. sectoria based on the size (Wang & Zhang 2015), but it also overlaps in size with P. minuta (Hayes 2000). This specimen could be attributed to P. sectoria because of the presence of the P1s, but it is on the smaller end of the body size distribution. However, the presence of the P1s has been shown to be a plastic character in this genus (Simpson 1946). Additionally, P. sectoria is traditionally known from the Oligocene while P. minuta is known from the Miocene (de Bonis 1981) further suggesting this specimen could be P. sectoria. However, this is called into question by the presence of P. sectoria in the Miocene of South Dakota (Harksen & MacDonald 1967) and reference to specimens of this species from the Eocene (Baskin & Tedford 1996; Boyd & Welsh 2014). The morphology of JODA 13221 also closely resembles a skull from the Oligocene White River Badlands of South Dakota (BADL 18581/SDSM 7118) which has also not been assigned to a specific species of Palaeogale (Benton et al. 2015). The teeth of JODA 13221 are not robust or large enough to be P. hyaenoides (Fejfar et al. 2003), or P. praehyaenoides (Morlo 1996). The skull clearly cannot belong to Cryptailurus, the other genus putatively in the Palaeogalidae, because the muzzle is narrow, P4 protocone is less developed, and the bullae are inflated and less flattened ventrally (Martin & Lim 2001).